Single oscillator transceiver frequency plan

ABSTRACT

A frequency plan is provided for particular use in a transceiver. Advantageously, a single oscillator may be used to generate desired frequency signal. One or more power splitters receive the signal and equally divide the signal into first and second signals having a frequency substantially equal to the original. Multipliers on each arm of the transceiver receive a signal and increase the frequency of the signal. Ultimately, multiple signals having different frequencies may be transmitted over the same cable due in part to the generated frequency separation between the signals. In one particular aspect, the frequency plan provides a two-thirds relationship between the frequencies of the multiple signals.

CROSS REFERENCE TO THE RELATED APPLICATIONS

This application includes subject matter that is related to and claimspriority from U.S. Provisional Patent Application Ser. No. 60/264,384,filed Jan. 26, 2001, under the same title.

FIELD OF INVENTION

The present invention relates, generally, to a system and method for afrequency plan, and in particular to a single oscillator frequency plan,and more particularly to a system and method for a single oscillatorfrequency plan configured to operate at frequencies below 3 GHz.

BACKGROUND OF THE INVENTION

In general, conventional transceiver frequency plans include twoseparate LOs (local oscillators) to drive mixers in the system andenable a wider range of frequency use. Multiple oscillators, however,are problematic. For example, oscillators have a tendency to drift(shift from the desired frequency range). A system containing two ormore oscillators will experience a drift in each oscillator at adifferent rate unless it is phase locked to a reference frequency. Thus,the exact transmit frequency of the system can unknowingly vary,resulting in a need for constant sampling of the transmit localoscillator. Moreover, as is common with most electrical equipment,increasing the number of elements or components increases hardware costsand consumes valuable PWB (printed wire board) space.

Accordingly, an improved system and method for a frequency plan in atransceiver system is needed. Specifically, a system and method for asingle oscillator transceiver frequency plan. In addition, a transceiverfrequency plan operable at lower frequencies is needed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription, appending claims, and accompanying drawings where:

FIGS. 1 and 2 illustrate, in block format, transceiver systemsimplementing exemplary frequency plans in accordance with the invention;

FIG. 3 illustrates, in block format, a transceiver system implementingan exemplary high side LO frequency plan in accordance with anembodiment of the invention; and

FIG. 4 illustrates, in block format, a transceiver system implementingan exemplary low side LO frequency plan in accordance with an embodimentof the invention.

DETAILED DESCRIPTION

The subject matter of the invention is particularly suited for use inconnection with complex mechanical and electrical systems, such assatellite communication systems. As a result, the preferred exemplaryembodiment of the present invention is described in that context. Itshould be recognized, however, that such description is not intended asa limitation on the use or applicability of the present invention, butis instead provided merely to enable a full and complete description ofa preferred embodiment.

An improved transceiver frequency plan system according to variousaspects of the invention is disclosed. Generally, a frequency plansystem of the exemplary embodiments mixes an IF (intermediate frequency)signal to a lower frequency range and separates the IF into, forexample, two signals that are distant enough from each other that bothsignals may be transmitted on the same cable without signal interferencefrom each other. In addition, a frequency plan system according tovarious embodiments may be configured to operate at desired frequencies,such as frequencies in the range where commonly available modemcomponents are available.

FIG. 1 illustrates, in block format, a transceiver system 100 accordingto one embodiment of the invention. System 100 implements a frequencyplan in accordance with the invention which generally includes a localoscillator (LO) 102, a power splitter 104, a plurality of mixers 106,108, 121 and 122, a plurality of amplifiers 110–116, a diplexer 118, anda cable 120. The local oscillator 102 may comprise any suitableoscillator configured to generate a range of desired frequencies. In onepreferred embodiment, implementation costs may be keep to a minimum byselecting a commonly available local oscillator. For example, currently,5 and 10 GHz LOs are readily available at reasonable costs.

Power splitter 104 may comprise any suitable component or combination ofcomponents configured to divide a power signal into two or more signals.Additionally, the divided signals have a frequency equal to, orsubstantially equal to, the frequency of the original signal.

Multipliers 106, 108, 121 and 122 are each represented in FIG. 1 as asingle element, however, it should be appreciated that each elementmerely demonstrates the function and is not intended to limit the scopeto a single element. In fact, the multipliers may comprise severalelements and/or stages of multiplication. Frequency multipliers(doublers) and their intended functions are well known in the industryand will not be discussed in detail.

In general, transmit multiplier, or mixer, 106 receives an IF signalfrom diplexer 118 and an LO signal from LO 102. Mixer 106 mixes thesignals and produces a radio frequency (RF) signal that is either thesum or the difference of the IF and LO frequency signals. In a similarmanner, receive mixer 108 combines a received RF signal with a receivedLO signal to produce an IF frequency signal.

One advantage of the invention is the ability to transmit multiple IFsignals, having different frequencies, onto a single cable withoutrisking interference among the signals. The unique frequency plan of theinvention helps to enable this to occur by providing sufficientseparation in frequency between the multiple IF signals to avoidinterference. In various embodiments of the invention, a two-thirds (⅔)relationship between the IF signal frequencies is established. Forexample, one signal is multiplied to be four times the original LOfrequency and a second signal is multiplied to be six times the LOfrequency, thus a four-to-six, or two-thirds relationship between thesignal frequencies.

In one particular embodiment of FIG. 1, multipliers 121 and 122 areconfigured to provide a two-thirds relationship between the frequenciesof their respective signal outputs. Recall that power splitter 104divides the original LO signal into substantially equal signals. In thepresent embodiment, power splitter 104 divides the received LO signalinto two signals with each signal having substantially the samefrequency as the original LO signal. One signal is received atmultiplier 121 and the second signal is received at multiplier 122. Inthis particular exemplary embodiment, multiplier 122 may be configuredto multiply the received signal by six and multiplier 121 may beconfigured to multiply the received signal by four. Therefore, afour-to-six or two-thirds relationship between the divided signals isestablished.

Amplifiers 110–116 may comprise any known or discovered amplificationdevice(s) or element(s). Amplifiers 110 and 112 may include the“transmitting arm” of the system and amplifiers 114 and 116 may suitablyinclude the “receiving arm” of the system. Typically there is some lossassociated with transceiving systems of the type depicted in FIG. 1 andof particular use for the present invention. Amplifiers 110–116 aresuitably configured to account for any signal loss and amplify thesignals accordingly. Signal loss may be due to line loss, interference,signal splitting and combining, and various other causes well known inthe communications industry.

In general, diplexer 118 enables the transmit and receive signals to becombined on the same cable. As previously stated, the frequency plan ofthe invention permits multiple signals of different frequency bands tobe combined without causing interference among the separate signals.Diplexer 118 and its combining function are known in the industry andmay be implemented as, for example, a pair of filters or a power dividerthat feeds separate filters.

Cable 120 comprises any suitable cable used for signal transmission. Forexample, a standard F connector with RG6 cable is well suited for thisapplication. While various types of cables may be used, in general, lowcost, readily available cable is often desirable. Currently, cables forsignal transmission below 3 GHz are readily obtainable for low cost usesuch as home satellite communication applications. In this manner,another advantage of the invention relates to the ability to transmitmultiple signals over a single cable with each signal transmitting at orbelow the desired 3 GHz.

In one particular application, transceiver system 100 is implemented ina ground satellite communication system comprising an outdoor unit andan indoor unit. In this application, cable 120 may extend from system100, the outdoor unit, to an indoor unit having a detector and othervarious components.

Referring now to FIG. 2, a transceiver system 200 in accordance withanother embodiment of the invention is illustrated. System 200 includessubstantially the same elements as system 100 of FIG. 1, exceptmultipliers 121 and 122 of FIG. 1 are now depicted as multipliers 208and 207 respectively, and mixers 106 and 108 are depicted as subharmonicmixers 206 and 209 respectively. As previously mentioned, themultipliers as described and illustrated herein, may comprise one ormore elements or devices configured to multiply the received signal. Forexample, in this particular embodiment, multiplier 207 is suitablyconfigured to multiply the received LO signal by three and subharmonicmixer 206 is suitably configured to further multiply the signal by 2.Thus, the divided signal from the original LO signal is now multipliedby 6. In a similar manner, multiplier 208 is suitably configured tomultiply the original LO signal by two and subharmonic mixer 209 issuitably configured to further multiply the signal by two. Thus, thesecond divided signal from the original LO signal is multiplied by four.Thereby, establishing a two-thirds relationship between the two dividedsignals.

FIG. 3 illustrates a transceiver system 300 in accordance with anotherembodiment of the invention. System 300 implements a transceiverfrequency plan in accordance with the invention and, in this particularembodiment, a “high side” frequency plan is illustrated. In general, ahigh side frequency plan receives and transmits an RF (radio frequency)signal which is lower in frequency than the multiplied LO signalfrequency. Conversely, a low side frequency plan receives and transmitsan RF signal which is higher in frequency than the multiplied LO signalfrequency. As will be discussed in further detail, both high and lowside frequency plans may be used with the transceiver frequency plan ofthe invention.

System 300 includes substantially the same elements as exemplary systems100 and 200, such as a local oscillator (LO) 302, a power splitter andmultiplier 303, a plurality of filters 308–312, multipliers 314 and 316,a plurality of amplifiers 318–328, a diplexer 330, and a cable 332.Unlike the previous examples, system 300 and the embodied exemplaryfrequency plan is shown and described with specific frequency ranges. Itshould be noted that this description and range of frequencies is in noway intended to be limiting on the disclosure or applicability of theinvention. Rather, the illustration and accompanying description areprovided merely to assist in understanding the invention. As should berealized, numerous combinations of elements and/or desired frequencyranges may be used in a frequency plan of the invention withoutdeparting from the overall spirit of the invention.

In one particular embodiment, LO 302 may comprise a dielectric resonatoroscillator (DRO) which is known in the industry. In the presentexemplary embodiment, LO 302 may include a 5.325 GHz DRO which, as willbe described below, is one example of an LO which enables the diplexedIF signals to be transmitted over cable 332 at a frequency less than 3GHz. While 5.325 GHz is conveniently described herein, this embodimentis not intended to be limiting and, in fact, other LOs may be equallysuited for the invention, e.g., 10 GHz LO.

Power splitter and multiplier 303 may be referenced as the “first stage”of power splitting and multiplying. In this embodiment, power splitterand multiplier 303 includes power dividers 304 and 306, multipliers 305and 307, and amplifiers 333 and 334. Power dividers 304 and 306 aresimilar in function as previously described power splitter 104, and maycomprise any suitable component or combination of components configuredto divide a power signal into two or more signals having a power levelequal to the original signal. Power divider 304 receives the LO signal(in this embodiment is a 5.325 GHz signal) and divides the signal intotwo substantially equal signals of 5.325 GHz each. One signal isreceived at multiplier 305 and the second signal is received atmultiplier 307. In one particular embodiment, multiplier 305 multipliesthe received signal by two, i.e., from 5.325 to 10.65 GHz. Themultiplied signal is then divided by power divider 306 into twosubstantially equal (10.65 GHz) signals. One of the 10.65 GHz signals isreceived at mixer 307, which is preferably a balanced mixer, and theother 10.65 GHz signal is filtered. Mixer 307 adds the 10.65 GHz signalwith a second 5.325 GHz signal received from power divider 304. Thus,power splitter and multiplier 303 receives a single LO signal andoutputs two LO signals; one signal equal to two times the original LOsignal (multiplied by two at multiplier 305) and one signal equal tothree times the original signal (multiplied by two at multiplier 305 andmixed with a signal equal to the original signal at mixer 307). In thisparticular example, one signal is multiplied from 5.325 GHz to 10.65 GHz(two times) and the second signal is multiplied from 5.325 GHz to 15.975GHz (three times). As mentioned earlier, it is common to experience somesignal loss during power splitting and combining, therefore, amplifiers333 and 334 are included to amplify the signal accordingly.

Filters 308 and 309 comprise any suitable bandpass filter. In general,filters are included to exclude spurious signals which commonly occurafter mixing, splitting and/or dividing signals. Filters 308 and 309suitably filter out spurs from the signals output from power splitterand mixer 303. The output of filter 308 (˜15.975 GHz or three times theLO signal frequency) and the output of filter 309 (˜10.65 GHz or twotimes the LO signal frequency) may be amplified by amplifiers 328 and326 respectively to account for any power loss.

In this embodiment, system 300 is suitably configured to operate in theK band frequency range. As previously mentioned, to clearly understandthe specific embodiment, a range of frequencies is provided. Thereceiving arm of the system may receive an RF signal in the frequencyrange of about 19 to 20 GHz and the transmitting arm of the system maytransmit at a frequency range from about 29 to 30 GHz. These transmitand receive bands are of particular interest for some applicationsbecause they coincide with the FCC assigned Internet access bands.

Multiplier 314 receives a signal that is substantially two times greaterin frequency than the original LO signal. In this embodiment, multiplier314 is a doubler and thus the resulting signal is now four times greaterthan the original LO signal, i.e., ˜21.3 GHz.

In a similar manner, multiplier 316 receives a signal that issubstantially three times greater in frequency than the original LOsignal. In this embodiment, multiplier 316 is a doubler and thus theresulting signal is now six times greater than the original LO signal,i.e., ˜31.95 GHz. In one particular embodiment, the multipliers, such asmultipliers 314 and 316, are subharmonic balanced mixers which provideLO rejection.

Multipliers 314 and 316 are additionally configured to present a roughlytwo-thirds (⅔) relationship between the two resulting signals. Forexample, in the present embodiment, the arm of the system containingmultiplier 314 is configured to result in a signal that is four timesthe original LO signal and the other arm containing multiplier 316 isconfigured to result in a signal that is six times the original LOsignal. Thus, a two-thirds ( 4/6) relationship exists between the twosignals.

Filters 310 and 312 are configured to allow those signals to pass whichrepresent the difference between the divided and multiplied LO signaland the transmitted RF signal. In this embodiment, the resulting signalfrom filter 312 is between 1.95 and 2.45 GHz (31.95 GHz–30 GHz; 31.95GHz–29.5 GHz) and the resulting signal from filter 310 is between 1.1and 1.6 GHz (21.3 GHz–20.2 GHz; 21.3 GHz–19.7 GHz). In this embodiment,the differences result in a signal frequency less than 3 GHz. This is apreferred situation due to the cable and industry standards. Forexample, in general, cables for transmitting signals in the frequencyranges of less than 3 GHz are currently less expensive, experience lessloss and are readily available for a wide variety of uses, e.g., homecommunications.

Diplexer 330 and its function may be similar to diplexer 118 describedherein.

Cable 332 comprises any suitable cable used for signal transmission andmay be of the same type as described herein for cable 120.

Referring now to FIG. 4, a transceiver system 400 in accordance withanother embodiment of the invention is illustrated. System 400implements a transceiver frequency plan in accordance with the inventionand, in this particular embodiment, a “low side” frequency plan isillustrated. The individual components of system 400 are similar innature to those of system 300 implementing a high side frequency planand thus will not be described again in detail. System 400, by industrydefinition, is a low side plan because the multiplied LO signal is lessthan the RF signal. It should be noted that each of the resultingsignals received at the diplexer are less than 3 GHz.

Similar to the previous examples, system 400 includes an LO 402, aplurality of multipliers 403, 406, 409, 411, 413 and 415, power dividers410 and 414, filters 408 and 412, and a plurality of amplifiers (notnumerical referenced). Additionally, system 400 is operating in the Kband frequency range, and in fact receives signals from multiple bandswithin the K band. In this particular illustration, one signal isreceived in the Internet access band and a second signal is received inthe home satellite access band, e.g., dish network and direct TV. Thisexample demonstrates the flexibility provided by a frequency plan of theinvention. For instance, a dual up-convert with “tack-on” capabilities.

Again, it should be appreciated that system 400 is shown with exemplaryfrequency ranges for illustrative purposes only. The ranges provides arenot intended to limit the scope of the invention, but merely to providea numeric understanding of one particular frequency plan of theinvention.

To fully understand the exemplary frequency plan of system 400, a briefexplanation of the illustrative frequencies will follow. Mixer 406 maybe implemented to produce an IF frequency signal that is the differenceof the LO signal received from LO 402 and the received RF frequencysignal. In this particular example, LO 402 may include a 11.25 GHzfree-running DRO and the received RF signal may be in the KuTV band.Thus, the resulting IF signal falls within the desired frequency rangeof below 3 GHz.

While not depicted in the Figures, a communications system such as anyof the systems 100, 200, 300 and 400 described herein may suitablyinclude additional back end and front end systems which are generallywell known in the communications industry, e.g., a signal detector,modem, and/or frequency counter. It should be appreciated that theparticular implementations shown and described herein are illustrativeof various embodiments of the invention including its best mode, and arenot intended to limit the scope of the present invention in any way. Forexample, the systems and methods for frequency plans described hereinwere generated for the FCC licensed band as shown, but it should beappreciated that other frequency allocations may be used. For the sakeof brevity, conventional techniques for signal processing, datatransmission, signaling, and network control, and other functionalaspects of the systems (and components of the individual operatingcomponents of the systems) may not be described in detail herein.Furthermore, the connecting lines shown in the various figures containherein are intended to represent exemplary functional relationshipsand/or physical couplings between the various elements. It should benoted that many alternative or additional functional relationships orphysical connections may be present in a communication system.

While the principles of the invention have now been made clear inillustrative embodiments, there will be immediately obvious to thoseskilled in the art many modifications of structure, arrangements,proportions, the elements, materials and components, used in thepractice of the invention which are particularly adapted for a specificenvironment and operating requirements without departing from thoseprinciples. These and other changes or modifications are intended to beincluded within the scope of the present invention, as expressed in thefollowing claims.

1. A frequency plan for a fully duplexed transceiver having atransmitted signal and a received signal, said plan comprising: a singleoscillator, associated with the fully duplexed transceiver, configuredto generate an oscillator signal at a desired frequency; a powersplitter configured to receive said oscillator signal and to divide saidsignal into first and second signals having a frequency substantiallyequal to said desired frequency of said oscillator signal; a firstmultiplier configured to receive said first signal and to increase thefrequency of said first signal; and a second multiplier configured toreceive said second signal and to increase the frequency of said secondsignal, such that the increased frequencies of said first and secondsignals represent a two-thirds relationship between the frequencies. 2.The frequency plan for a transceiver of claim 1, wherein saidtransmitted and said received signals comprise K band frequencies. 3.The frequency plan for a transceiver of claim 1, wherein saidtransmitted and said received signals comprise Ka band frequencies. 4.The frequency plan for a transceiver of claim 1, wherein saidtransmitted and said received signals comprise different frequencies. 5.The frequency plan for a transceiver of claim 1, further comprising afirst filter coupled to said first multiplier and a second filtercoupled to said second multiplier.
 6. The frequency plan for atransceiver of claim 5, wherein said first filter being configured topass a first filtered signal having a frequency representing adifference between said received signal frequency and said increasedfrequency of said first signal.
 7. The frequency plan for a transceiverof claim 6, wherein said second filter being configured to pass a secondfiltered signal having a frequency representing a difference betweensaid transmitted signal frequency and said increased frequency of saidsecond signal.
 8. The frequency plan for a transceiver of claim 7,wherein said first and second filtered signals comprising frequencies ator below 3 GHz.
 9. The frequency plan for a transceiver of claim 7,wherein said first and second filtered signals having differentfrequencies are transmitted over a single cable at the same time. 10.The frequency plan of claim 1, wherein said received signal comprisesfirst and second received signals and wherein said first received signalcomprises a Ka band frequency and said second received signal comprisesa Ku band frequency.
 11. The frequency plan of claim 1, wherein saidsingle oscillator is a single free running local oscillator.
 12. Thefrequency plan of claim 11, wherein said single free running localoscillator is allowed to drift.
 13. A transceiver system comprising: areceiving section configured to receive a signal comprising a receivedfrequency; a transmitting section configured to transmit a transmittedsignal comprising a transmitted frequency and said received andtransmitted frequencies being different; a single oscillator configuredto generate an oscillator signal at a desired frequency; a signalsplitter configured to divide said oscillator signal into twosubstantially equal oscillator signals; a first multiplier configured toreceive one of said oscillator signals and to increase a frequency ofsaid oscillator signal; a second multiplier configured to receive theother oscillator signal and to increase a frequency of said otheroscillator signal; a receiving filter of said receiving sectionconfigured to pass a received filtered signal having a frequencyrepresenting a difference between said received signal frequency andsaid first multiplied signal; and a transmitting filter of saidtransmitting section configured to pass a transmitted filtered signalhaving a frequency representing a difference between said transmittedsignal frequency and said second multiplied signal, wherein saidreceived and transmitted filtered signals having different frequenciesand being communicated simultaneously over a single cable; wherein theincreased frequencies of said oscillator signals represent a two-thirdsrelationship between the frequencies.
 14. The transceiver system ofclaim 13, wherein said received and transmitted frequencies comprise Kband frequencies.
 15. The transceiver system of claim 13, wherein saidreceived and transmitted frequencies comprise Ka band frequencies. 16.The transceiver system of claim 13, wherein said received andtransmitted filtered signals comprising frequencies at or below 3 GHz.17. A ground satellite communication system operating in the K bandfrequencies said system comprising: an indoor unit and an outdoor unitin communication with said indoor unit, said outdoor unit comprising atransceiver system having: a single oscillator configured to generate anoscillator signal at a desired frequency; a signal splitter configuredto receive said oscillator signal and to divide said signal into twosubstantially equal oscillator signals; a receiving section configuredto receive a signal comprising a received frequency, said receivingsection coupled to a first multiplier configured to receive one of saidoscillator signals and to increase the frequency of said oscillatorsignal, a receiving filter of said receiving section configured to passa received filtered signal having a frequency representing a differencebetween said received signal frequency and said first multiplied signal;a transmitting section configured to transmit a signal comprising atransmitted frequency different than said received frequency, saidtransmitting section coupled to a second multiplier configured toreceive the other oscillator signal and to increase the frequency ofsaid other oscillator signal such that the increased frequencies of saidtwo oscillator signals represent a desired multiple between the twosignals, a transmitting filter of said transmitting section configuredto pass a transmitted filtered signal having a frequency representing adifference between said transmitted signal frequency and said secondmultiplied signal; wherein the increased frequencies of said oscillatorsignals represent a two-thirds relationship between the frequencies; anda diplexer configured to receive said received and transmitted filteredsignals and to pass said filtered signals of different frequencies to asingle cable for duplex communication to said indoor unit.
 18. A signaltransceiving method comprising: receiving a signal having a firstfrequency; generating an oscillator signal from a single oscillator,associated with a fully duplex transceiver; dividing said oscillatorsignal into a first divided oscillator signal and a second dividedoscillator signal, wherein said first and second divided oscillatorsignals have substantially the same frequency as said generatedoscillator signal; increasing the frequency of the first dividedoscillator signal to obtain a first desired multiple of said firstdivided oscillator signal; increasing the frequency of the seconddivided oscillator signal to obtain a second desired multiple of saidsecond divided oscillator signal; wherein said first desired multipleand said second desired multiple represent a two-thirds relationship;filtering said received signal and said first divided oscillator signalto obtain a filtered signal having a frequency at or below 3 GHz;filtering a transmission signal and said second divided oscillatorsignal to obtain a transmitted signal having a second frequency that isdifferent from said first frequency of said received signal and saidtransmission signal being at or below 3 GHz and having a differentfrequency than said filtered signal; and transmitting said transmittedsignal.
 19. The transceiving method of claim 18, further comprisingcommunicating over a single cable said filtered signal and saidtransmission signal.
 20. The transceiving method of claim 18, whereinsaid first and second frequencies comprise K band frequencies.
 21. Thetransceiving method of claim 18, wherein said first and secondfrequencies comprise FCC assigned Internet access frequency bands.
 22. Asignal transceiving method comprising: receiving a signal having a firstfrequency; generating an oscillator signal from a single oscillator,associated with a fully duplex transceiver, wherein said singleoscillator is a single free running local oscillator; dividing saidoscillator signal into a first divided oscillator signal and a seconddivided oscillator signal, wherein said first and second dividedoscillator signals have substantially the same frequency as saidgenerated oscillator signal; increasing the frequency of the firstdivided oscillator signal to obtain a first desired multiple of saidfirst divided oscillator signal; increasing the frequency of the seconddivided oscillator signal to obtain a second desired multiple of saidsecond divided oscillator signal wherein said first desired multiple andsaid second desired multiple represent a two-thirds relationship;filtering said received signal and said first divided oscillator signalto obtain a filtered signal having a frequency at or below 3 GHz;filtering a transmission signal and said second divided oscillatorsignal to obtain a transmitted signal having a second frequency that isdifferent from said first frequency of said received signal and saidtransmission signal being at or below 3 GHz and having a differentfrequency than said filtered signal; and transmitting said transmittedsignal.